Neset Acarkan

The uranium(VI) extraction mechanism of D2EHPA-TOPO from a wet process phosphoric acid

This paper reports the results of an investigation into the solvent extraction of uranium from technical grade phosphoric acid using industrially available extractants as D2EHPA and TOPO diluted in technical grade kerosene. Preliminary tests showed that, the effect of different parameters such as uranium oxidation stage, temperature and the molar ratio of D2EHPA/TOPO on the uranium recovery was in good agreement with those of previous investigations. However, a detailed investigation into the effect of phosphoric acid concentration, organic concentration and acid/organic phase ratios suggested that the mechanism of D2EHPA/TOPO synergism was rather complex and it presented a different character depending on the acid concentration.

The Effect of Collector's Type on Gold and Silver Flotation in a Complex Ore

Gold and silver are recovered by gravity concentration, cyanidation, or flotation from ores. The choice of those processes depends on the mineralogical characterization as well as gold and silver contents of the ore. Flotation has been applied on ores containing free gold and silver particles for many years. The flotation efficiency of gold and silver particles depends on the modifiers and collectors. This paper presents the results of the effect of different collector combinations on gold and silver recoveries from lead and zinc ores by flotation. Best results were obtained on the use of Aero 208 + Aerophine 3418 A as collectors at the dosages of 350 + 350 g/t and 1000 g/t Na2SiO3 as a depressant at pH 4.5 where particle size was below 38 µm. According to the process, a concentrate assaying 1026.9 g/t Au and 10185 g/t Ag was obtained. On the other hand, a concentrate containing 50.6% Pb was obtained with 39.7% recovery using potassium amyl xanthate (KAX) and aminothiophenol (ATP). This concentrate graded 235 g/t Au and 3740 g/t Ag.

The role of protective alkalinity and Ca2+ ions in the cyanidation of refractory silver ores

Abstract The effect of protective alkali on the extraction of silver from refractory ores, taken from the Kutahya-Gumuskoy region of Turkey, and the behaviour of dissolved Ca2+ ions during cyanidation were investigated. It was shown that high concentrations of protective alkali are beneficial in the cyanidation of these ores, in contrast to gold cyanidation where they prohibit gold dissolution. Calcium ions are advantageous in the cyanidation of sulphidic silver ores since they prevent the detrimental effects of ions which hinder silver dissolution and consume CN− ions. Using high concentrations of protective alkalis decreases the cyanide consumption.

STUDY OF THE SETTLING OF TINCAL MINERAL PARTICLES IN DIFFERENT FLUID MEDIA

The aim of this study is to investigate the behavior and velocity ratio of tincal particles in different fluid media containing clay minerals, so that the diversion of tincal particles into slime product or not can be estimated. Tests were carried out using a settling unit and parameters such as clay content of the pulp and dissolved tincal concentration were investigated. Test results were evaluated by measuring the particle-size distribution in the settled product at the end of predefined durations. Average particle size of the settling product at the end of 8 min was observed to be 35 µm at 5% solids ratio by weight in the pulp; however, it was 55 µm at 20% solids ratio by weight. On the other hand, the presence of clay in the fluid medium was observed to directly affect the settling rate of the particles. In the suspension containing 100 g/l of clay and 5% of tincal, particle size of the settling fraction was 55 µm at the end of 8 min, which well compared to 35 µm in the clay-free suspension. The classification medium that contained considerable amounts of clay acted as a heavy and viscous medium and it was determined that fine tincal particles were lost into the tailings during the classification processes in Kırka Tincal Concentrator.

SOLVENT EXTRACTION OF URANIUM FROM WET PROCESS PHOSPHORIC ACIDS

In this investigation solvent extraction of uranium from wet process phosphoric acids was realized using industrially available organic extracts 2-Ethylhexyl phosphoric acid (D2EHPA) and Tri-n-octyl phospine oxide (TOPO). The results of initial tests showed that, the effect of different parameters such as uranium oxidation stage, temperature and the molar ratio of D2EHPA/TOPO on the uranium recovery was in good agreement with those of previous investigations. The effect of acid concentration and acid/organic phase ratios suggested that the mechanism of D2EHPA/TOPO synergism was rather complex and it presented different trends.